Clearing the Air

Willamette University student Elizabeth Hart cares about the environment. She spent her summer at Duke University in Durham, N.C., studying the effects of increased carbon dioxide on plants. She learned plenty about plants - and even more about herself.

Hart, a sophomore who studies environmental science at Willamette, was one of only 30 students across the country selected to participate in the Department of Energy's Global Change Education Program. The national 10-week program, which provides a $5,000 stipend plus travel expenses, offers undergraduates the opportunity to work with some of the top global change researchers in the country. Hart traveled to Durham to work with biology professor Rob Jackson of Duke University.

"We were looking at the effects of different concentrations of carbon dioxide [CO2] on fungal growth on trees in the forest," explains Hart, who spent about half her time working in the laboratory at Duke University and half working in the project's forest test plots. "In the forest, we sectioned off six plots of trees 30 meters in diameter and fumigated three of them with elevated levels of CO2."

Hart was looking at maple leaf spot (Phyllosticta minima), a common fungal infection that causes round lesions with tan centers and dark rims on the leaves of a number of different types of maple trees. To measure fungal growth, Hart took before and after pictures of the leaves. "I used the computer to analyze the pictures, including the size of the lesions," she says.

Additionally, she grew the fungus in the lab. "I worked in the greenhouse growing the fungus on plates in chambers," she says. "I exposed them to different levels of carbon dioxide. Some levels of CO2 were the same as the ambient air [normal air]; others were levels we project for CO2 in the next 50 years."

What she found was troubling and could have long-term implications for the environment. "Leaves exposed to increased CO2 develop a waxier leaf surface so it's harder for the fungus to navigate across the leaf and infect it through the stomata openings, which mean the leaves have less fungal infection," she says. "But the stomal openings also decrease in size and density."

The stomata, microscopic pores found on the underside of leaves and on stems of plants, permit gas exchange with the air. They're vitally important for the plant's respiration, evaporation of water and for photosynthesis, the process by which plants make oxygen and carbohydrates for food from carbon dioxide and water. Clog the pores with CO2 and the plants can't do their job.

"It's obvious that the plants try to protect themselves from the increased CO2," she says. "They were successful in protecting themselves more from the fungal growth, but how are increased CO2 levels going to affect things like the overall growth of the plants?"

One of the best aspects of her summer research experience was meeting other undergraduates interested in science and global change from all over the country. "I loved meeting all the other students at the orientation and then at the end of the project when we did our presentations," she says. "It was great learning what other students had done during the summer, what they were interested in and what they plan on doing in the future."

As for Hart's future, she's not firm on her direction, but her summer research experience has given her clues. "I valued the experience of working in the lab and doing research, but I realized I probably couldn't make a career out it," she says. "The experience gave me a lot more confidence and taught me more about the direction I want to head in. Now I know that I want to do work that encompasses the broader scientific picture."

Hart, who plans to apply for another research internship next summer, says the experience has also heightened her concern for our environment. "We need to know how our environment reacts to our way of living in this world, including our everyday use of automobiles, factory emissions and everything else combined," she says. "I don't want to ruin our environment for future generations."